(1) Field of the Invention
The present invention relates to a pressure-filling system for filling a tank, and to a vehicle provided with the system. More particularly, the invention may be applied to an aircraft. However, it should be understood that the filling system may be adapted to any type of structure that includes a tank.
In particular, the invention applies to the technical field of pressure-filling systems that include a device for avoiding excess pressure in a tank.
(2) Description of Related Art
A tank may comprise a single container that is fed with fluid by the pressure-filling system. In a variant, the tank may comprise a plurality of interconnected containers, with at least one container being fed directly by the pressure-filling system.
An aircraft, and in particular a helicopter type rotorcraft, usually includes gravity filler means in order to fill a tank using rudimentary means, e.g. a simple pipe. Conventionally, gravity filler means comprise an inlet duct opening out to a screen so as to avoid filling the tank with all kinds of pollutant.
The drawback of such gravity filling lies in particular in the time taken for filling, which remains relatively long.
In parallel, the fuel-filling system is optionally provided with a pressure-filling valve.
Means for delivering fluid under pressure are then connected to the pressure-filling valve via a catch wheel so as to enable the tank to be filled very quickly. A tanker truck is usually used to fill the tank with a fluid under pressure.
Document EP 2 364 911 presents a mixed system making it possible to fill a tank under pressure or by gravity.
The pressure-filling valve may include a mechanical or automatic end-of-filling control device, so as to end pressure filling.
Such an automatic end-of-filling control device may comprise a gauge system for determining whether the volume of fuel in the tank has reached a predetermined threshold. Under such circumstances, if the threshold is reached, the pressure-filling valve is closed automatically.
Furthermore, the pressure-filling system may include a device for mitigating a failure of the end-of-filling control device.
In the event of a failure of the end-of-filling control device, the pressure of the fuel in the tank increases. Such a failure may thus lead to rupture of a container of the tank, or of the structure surrounding the tank, for example.
Furthermore, it is also possible to program the quantity of fuel to inject into a tank by using a programmer of a tanker truck. Malfunctioning of the programming may also lead to excess pressure in the tank.
A pressure-filling system may thus include a valve for limiting the pressure in the tank. Such a valve is sometimes referred to as a “pressure relief valve”.
When the pressure existing in a tank reaches a threshold defined by the manufacturer, the pressure relief valve opens so as to avoid an incident.
However, it is sometimes difficult to arrange a pressure relief valve. For example, a pressure relief valve of an aircraft must be designed to comply with regulations relating to crash situations. It is therefore difficult to calibrate the pressure relief valve, since the pressure inside the tank might rise either as a result of a failure of an end-of-filling control device or as a result of a crash.
Furthermore, a pressure relief valve is rather bulky and must be inspected regularly.
Furthermore, a pressure relief valve itself might fail.
Document U.S. Pat. No. 5,289,900 describes a filling device that is provided with a pressure-filling valve that communicates with a tank by means of a pipe having reference “52”.
Documents U.S. Pat. No. 3,643,690 and FR 2 731 185 are also known, and remote from the field of the invention.